Ion milling coupled field emission scanning electron microscopy reveals current misunderstanding of morphology of polymeric nanoparticles

Focused ion beam-scanning electron microscopy provides novel insights of drug delivery phenomena

Scanning electron microscopy (SEM) has long been a standard tool for morphological analyses, providing sub micrometer resolution of pharmaceutical formulations. However, analysis of internal morphologies of such formulations can often be biased due to the introduction of artifacts that originate from sample preparation. A recent advancement in SEM, is the focused ion beam scanning electron microscopy (FIB-SEM). This technique uses a focused ion beam (FIB) to remove material with nanometer precision, to provide virtually sample-independent access to sub-surface structures. The FIB can be combined with SEM imaging capabilities within the same instrumentation. As a powerful analytical tool, electron microscopy and FIB-milling are performed sequentially to produce high-resolution 3D models of structural peculiarities of diverse drug delivery systems or their behavior in a biological environment, i.e. intracellular or -tissue distribution. This review paper briefly describes the technical background of the method, outlines a wide array of potential uses within the drug delivery field, and focuses on intracellular transport where high-resolution images are an essential tool for mechanistical insights.

Adalimumab Decorated Nanoparticles Enhance Antibody Stability and Therapeutic Outcome in Epithelial Colitis Targeting

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract with increasing incidence worldwide. Although a deeper understanding of the underlying mechanisms of IBD has led to new therapeutic approaches, treatment options are still limited. Severe adverse events in conventional drug therapy and poor drug targeting are the main cause of early therapy failure. Nanoparticle-based targeting approaches can selectively deliver drugs to the site of inflammation and reduce the risk of side effects by decreasing systemic availability. Here, we developed a nanoparticulate platform for the delivery of the anti-TNF-α antibody adalimumab (ADA) by covalent crosslinking to the particle surface. ADA binding to nanoparticles improved the stability of ADA against proteolytic degradation in vitro and led to a significantly better therapeutic outcome in a murine colitis model. Moreover, immobilization of ADA reduced systemic exposure, which can lead to enhanced therapeutic safety. Thus, nanoparticle protein decoration constitutes a platform through which epithelial delivery of any biological of interest to the inflamed gut and hence a local treatment can be achieved.

Polymeric matrix hydrophobicity governs saponin packing-density on nanoparticle surface and the subsequent biological interactions

This study investigated the loading behavior of Quillaja saponin as a model surface-active cargo on (NP) nanoparticles prepared with various hydrophobic polymers and using different organic solvents through emulsification/solvent evaporation, and the impact of NP surface hydrophobicity upon the cytotoxic and hemolytic properties of the loaded entity. A superficial monolayered arrangement of saponins on NP was established (R² > 0.9) for all NP, as the saponin loading values complied with the Langmuir adsorption isotherm over the entire concentration range. Next, based on the measurement of interfacial tension between formulation phases, and the subsequent use of Gibb's adsorption isotherm, the packing density (Г_exc) and loading of saponins on various nanospheres could be predicted with good correlation with the actual values (R² > 0.95). The results demonstrated that the hydrophobicity of the polymeric matrix was the major determinant of saponin packing density on the nanospheres. Finally, the impact of NP surface properties upon saponin biological interactions was investigated, where a linear correlation was found between the NP surface hydrophobicity and their hemolytic properties (R² ≅ 0.79), and cytotoxicity against two cancer cell lines (R² > 0.76). The surface hydrophobicity of the polymeric NP seemingly governed the NP-cell membrane binding, which in turn determined the amount of membrane-bound saponins per unit NP surface area. As the saponins exert their cytotoxicity mainly through strong permeabilization of the cell membrane, a higher amount of NP-membrane association governed by a more hydrophobic matrix can lead to higher levels of cytotoxicity. These findings highlight the importance of a detailed characterization of NP surface properties, particularly in case of surface-active cargos, for these dictate the side effects and biological interactions of the delivery system.

Inbuilt novel bioretardant feature of biopolymer isolated from cucumis sativa for designing drug loaded bionanosuspension

Objectives: The current research work has potential for delivery of fluvoxamine moiety in bio-nanosuspension mode for the effective treatment of depression. Depression is a mood disorder characterized by persistently low mood and a feeling of sadness and loss of interest. Methods: The fluvoxamine loaded bio-nanosuspension was prepared using novel bio-retardant isolated from fruit pulp of Cucumis sativa by a novel method with different ratios (1:1, 1:2, 1:3, 1:4, 1:5) and the same ratios with standard polymer eudragit L-100. The bio-nanosuspensions were evaluated for pH stability studies, percentage entrapment efficacy, in vitro drug release, particle size, polydispersity index, zeta potential, and stability studies. Results: The bio-nanosuspension was subjected to the best formulation based on comparison of above mentioned evaluation parameters, and the Fc1 (1:1) formulation was found to be the best formulation. Cucumis sativa provided excellent stability for the formulation, and the resulting particle size was found to be 194 nm. The bio-nanosuspension had a Polydispersity Index (PDI) of 0.13 with zeta potential of -17.9 mV. Conclusion: The fluvoxamine loaded bio-nanosuspension using Cucumis sativa was found to be nontoxic and compatible with drug delivery systems for treatment of depression. This was the first report in which Cucumis sativa as a bioretardant demonstrated greater retardability over the standard polymer eudragit-100.

Collagenase loaded chitosan nanoparticles for digestion of the collagenous scar in liver fibrosis: The effect of chitosan intrinsic collagen binding on the success of targeting

A variety of hepatic insults result in the accumulation of collagen-rich new extracellular matrix in the liver, ultimately culminating in liver fibrosis and cirrhosis. For such reasons, approaches looking into digestion of the collagen-rich extracellular matrix present an interesting therapeutic approach for cases of chronic liver disease, where the fibrotic scar is well established. Portal collagenase administration has recently led to the successful reversion of cirrhosis in an experimental rabbit model. Notwithstanding, the question of how such a sensitive therapeutic macromolecule could be administered in a less invasive manner, and in a way that preserves its functionality and avoids digestion of other non-hepatic vital collagen presents itself. Chitosan is a biodegradable polymer that has been reported to interact and bind to collagen. Chitosan nanoparticles (CS NPs) have also been reported to encapsulate therapeutic proteins, maintaining their functional form and protecting them from in-vivo degradation. For such reasons, CS NPs were loaded with collagenase and evaluated in-vitro and in-vivo for their ability to target and digest collagen. CS NPs were able to encapsulate collagenase (≈ 60% encapsulation efficiency) and release its content in active form. To determine whether chitosan's collagen interaction would enable NP collagen binding or whether the modification with collagen binding peptides (CBPs) is necessary, CS NPs were modified with the CBP; CCQDSETRTFY. Since the density of targeting ligand and the length of tether play a significant role in the success of active targeting, the surface of NPs was modified with different densities of the CBP either directly or using a polyethylene glycol (PEG) spacer. PEGylated NPs showed higher levels of CBP tagging; high, intermediate and low density of CBPs corresponded to 585.8 ± 33, 252.9 ± 25.3 and 56.5 ± 8.8 µg/mL for PEGylated NPs and 425.56 ± 12.67, 107.91 ± 10.3 and 49.86 ± 3.2 µg/mL for unPEGylated NPs, respectively. In-vitro collagen binding experiments showed that unmodified CS NPs were able to bind collagen and that modification with CBPs either directly or via PEG did not enhance collagen binding. In-vivo experiments demonstrated that unmodified CS NPs were able to reverse fibrosis with a survival rate of 100% at the end of the study, indicating the ability of CS NPs to deliver functional collagenase to the fibrotic liver and making the use of CBPs unnecessary.

Design of selegiline-loaded bio-nanosuspension for the management of depression using novel bio-retardant from Manilkara zapota

Objective: Depression is one of the most frequent psychiatric and potentially life-threatening disorders. This research work can offer a potential for delivery of selegiline moiety via ocular route in bio-nanosuspension mode for the effective management of depression after preclinical performance screening. Methods: The selegiline-loaded bio-nanosuspension was prepared using novel bio-retardant isolated from fruit pulp of Manilkara zapota (Sapodilla) by sonication solvent evaporation method with different ratios (0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 1%) and with standard polymer HPMC (0.1%, 0.2%, 0.3%, 0.4%, and 0.5%). The prepared formulations were evaluated for pH stability studies, %entrapment efficiency, in vitro drug release, particle size, polydispersity index (PDI), zeta potential, and stability studies. Results: The prepared bio-nanosuspension was subjected to the best formulation based on comparison of above-mentioned evaluation parameters, so Fb2 (0.1%) formulation was found to be the best formulation showing an R² value of 0.9814, T50% of 29.7 h, and T80% of 65.25 h. According to the release kinetics, the best fit model was found to be the Korsmeyer-Peppas with the Fickian diffusion (Higuchi matrix) as the mechanism of drug release. Manilkara zapota (Sapodilla) provided excellent stability for the formulation and resulting particle size for the best formulation was found to be 252 nm. The bio-nanosuspension had PDI of 0.35 with zeta potential of -8.91 mV. Conclusion: The prepared bio-nanosuspension was found to be safe and compatible with the ophthalmic delivery for treatment of depression.

Nanoparticles as drug carriers: current issues with in vitro testing

Incorporation of nanotechnology in the field of drug delivery has created exciting opportunities for the purposeful design of nanocarriers with potentials such as targeted delivery or controlled release of the incorporated cargo, improvement of bioavailability and reduction of therapeutic side-effects. Prior to in vivo administration, nanocarriers should undergo a set of in vitro evaluation procedures to ensure their stability, safety, conformity and ability to fulfill the desired mission. In this paper, current issues with in vitro evaluation techniques used for nanocarrier characterization (assessment of particle size, surface charge, drug release and toxicity) will be discussed. Furthermore, sufficiency of in vitro evaluation procedures for the prediction of in vivo scenarios and the necessary considerations to improve the correlation between the two settings will be debated.

Nanosuspensions of poorly water-soluble drugs prepared by bottom-up technologies

In recent years, nanosuspension has been considered effective in the delivery of water-soluble drugs. One of the main challenges to effective drug delivery is designing an appropriate nanosuspension preparation approach with low energy input and erosion contamination, such as the bottom-up method. This review focuses on bottom-up technologies for preparation of nanosuspensions. The features and advantages of drug nanosuspension, including bottom-up methods as well as the corresponding characterization techniques, solidification methods, and drug delivery dosage forms, are discussed in detail. Certain limitations of commercial nanosuspension products are also reviewed.